A、Summary （1）Technical performance）： Axial-flow fan promoted by state committee is a high efficiency low pressure fan. This kind of fan has the characteristics of low power consumption, low noise, good corrosion resistance and so on. It can be applied in industrial plants, industry of machinery manufacturing, chemical, printing and dyeing, electroplating, pharmaceutical and buildings of theatres, hotels, office, residence. If the wind shell is removed,it can also be used as a electric fan. It can also be installed in series in long exhaust pipes in order to increase the total pressure in the pipeline. （2）The fan type： Axial-flow fan are divided into NO2.8, NO3.15, NO3.55, NO4, NO4.5, NO5, NO5.6, NO6.3, NO7.1, NO8, NO9, NO10, NO11.2, total 13 types according to the impeller diameter. Each type has 4 pieces blades. Blade can fit into five angle including 15 °, 20 °, 30 °, 35 °. Because of different blade angle and spindle speed, wind pressure, air volume and the power consumption of fan are also different. For driving mode, we select different grades electric motors and join with the impeller directly. Shell of motor body is made into cylinder. The direction of rotation is clockwise. B、Maintenance of axial-flow fan 1.Before installation，you should check whether the fan is damaged and deformed due to the packing and shipping. The fan can only be installed after being repaired properly. When installing, you should pay attention to check the associated part of the presence of loose. Gap between blade and hair dryer should be even. Blade and hair dryer won’t touch. 2.You should add other support for weight of tube connecting to air outlet.It shouldn’t be withstand by hair dryer. 3.You must install air receiver and protection wire entanglement on the entrance of axial-flow fan. 4.Fan pedestal and ground plane must touch naturally. It can’t be combined by bolts in case pedestal deformation. You should revise the fan base through levelling instrument and add pad when necessary and then tighten the foundation bolts. 5.This axial-flow fan can’t be used before installing well. It must be tested after installation. 6.You must check whether connection parts is reliable and test the fan again if you don’t use the fan for a long time. 7.You should check bolts and sheath of wire annually after the fan operating normally and repair them according to specific conditions. 8.Pay attention to abnormal sound and vibration of fan when it is running and fix them in time.